Isolation Of Organophosphorus Pesticides Bacteria Degraders From Agricultural Sicilian Soils.

Abstract

Pesticides are generally categorized according to their great or low persistence in the environment. Although new biological, chemical, and management technologies are continually being developed to provide more sustainable production alternatives, it is expected that the use of pesticides will continue to be an essential tool in the integrated pest management. Pesticides are biologically active compounds designed to interfere with metabolic processes. Organophosphorus pesticides (OP) pesticides are less persistent than Organochlorine pesticides (OC), they are not without environmental risks, so this justifies the social concern about their level in different kind of matrices like soil, water and ground water. The aim of this study was to evaluate the biodiversity of OP degrader bacteria in Mediterranean agricultural soils. 47 isolates were obtained from enrichment cultures containing parathion or dimethoate as an exclusive carbon source. The isolates were grouped into 17 Operational Taxonomic Units (OTU) on the base of the ribosomal internal transcribed spacer (ITS) polymorphism. A positive and significative correlation was found between bacterial biodiversity and soil physical-chemistry characteristics. The strains, identified by partial sequencing of 16S rRNA gene, were tested in order to evaluate their pesticide degrading ability in mineral salt medium (MSM) by using solid-phase-micro-extraction (SPME) coupled with gas-chromatography mass-spectrometry (GC-MS). Some of the degrader isolates are not mentioned in organophosphorus degradation. Degenerated primers were used to identify the genes encoding organophosphorus hydrolase. The degradation capability of the selected strains were elucidated as possible biodegraders in contaminated standard soil microcosms, characterized by different physical chemicals characteristics.